Convert Darknet/YOLO .cfg and .weights files to .onnx files. More...

Convert Darknet/YOLO .cfg and .weights files to .onnx files.
Over time, I'm hoping other people will show up to help shine light in the dark corners, or provide me with more configurations and weights that are broken to help make this tool work better. As you'll no doubt see in the code below, there are many places where I've left some "todo" comments in an attempt to document code that needs to be fixed.
Stephane Charette, 2025-08-18.